Пытаюсь сделать 3D игру на ursina

Вот код:

from ursina import *
from ursina.editor.level_editor import y
from ursina.prefabs.first_person_controller import FirstPersonController

app = Ursina()

class Voxel(Button):
    def __init__(self, position=(0,0,0)):
        super().__init__(
            parent = scene,
            position = position,
            model = 'cube',
            origin_y = .5,
            texture = 'white_cube',
            color = color.color(0, 0, random.uniform(.9, 1.0)),
            highlight_color = color.lime,
        )

    def input(self, key):
        if self.hovered:
            if key == 'left mouse down':
                voxel = Voxel(position=self.position + mouse.normal)

            if key == 'right mouse down':
                destroy(self)


for z in range(8):
    for x in range(8):
        voxel = Voxel(position=(x, y,z))

player = FirstPersonController()
app.run()

Получаю ошибку:

Traceback (most recent call last):
  File "/home/meliorator1333/PycharmProjects/3Dproekt/code/main.py", line 2, in <module>
    from ursina.editor.level_editor import y
  File "/home/meliorator1333/PycharmProjects/3Dproekt/venv/lib/python3.8/site-packages/ursina/editor/level_editor.py", line 1199, in <module>
    level_editor = LevelEditor()
  File "/home/meliorator1333/PycharmProjects/3Dproekt/venv/lib/python3.8/site-packages/ursina/editor/level_editor.py", line 122, in __init__
    self.origin_mode_menu = ButtonGroup(['last', 'center', 'individual'], min_selection=1, position=window.top)
  File "/home/meliorator1333/PycharmProjects/3Dproekt/venv/lib/python3.8/site-packages/ursina/prefabs/button_group.py", line 27, in __init__
    self.select(self.buttons[i])
IndexError: list index out of range

Что в таком случае делать?